In communications networks, there may be a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communications network is deployed.
For example, transmission and reception schemes based on using narrow beam transmission and reception might be needed at comparatively high carrier frequencies to compensate for comparatively high propagation losses that might be present for transmission and reception using such high carrier frequencies. In a communications network where the transmission and reception point (TRP) of the network node at the network side uses narrow beams for transmission one of the narrow transmission beams is assumed to be discovered and monitored for each served wireless device at the user side. This process of discovering and monitoring is referred to as beam management. In order to perform beam management the network node uses measurements, as obtained and reported by the served wireless devices, on downlink reference signals such as channel state information reference signals (CSI-RS). The reference signals used for beam management can be transmitted periodically, semi-persistently or aperiodically (such as when being event triggered) and they can be either shared between multiple wireless devices (users) or be user-specific. In order for a wireless device to find a suitable transmission beam the network node could transmit CSI-RS in different transmission beams on which the wireless device performs measurements and reports back the N≥1 best transmission beams (where the value of N can be configured by the network node).
For example, one periodic beam sweep could span all directions served by the TRP, where the transmission beams of the periodic beams sweep are shared by all wireless devices served by the TRP in order to reduce overhead (compared to only having aperiodic user-specific beam sweeps). One purpose of the periodic beam sweep is for the network node to obtain an estimate of an initial direction to each wireless device. Such an initial direction is needed, for example, when a new wireless device enters the region served by the TRP, or when a wireless device comes back from idle mode. In idle mode, the network loses all beam related information to the wireless device. After an initial direction of the wireless device has been estimated, transmission of reference signals using more accurate aperiodic user-specific beams can be made.
After the transmission of the periodic beam sweep each wireless device has to report back the N best transmission beams to the TRP. However, in some cases the TRP only can listen in one reception beam at a time. Since the network node does not know in which direction the wireless devices are located it does not know which reception beam to use at the TRP for each respective wireless device.
Hence, there is still a need for an improved beam management.